1. Field of the Invention
The present invention relates to a semiconductor device having a substrate onto which a plurality of semiconductor chips are flip-chip bonded and a manufacturing method thereof, and more particularly, to the semiconductor device and the manufacturing method thereof which are suitable for yield enhancement.
2. Description of the Related Art
In recent years, the downsizing of a semiconductor device itself has been demanded as the downsizing and sophistication of electronic equipment and communications equipment employing the semiconductor device have been in progress. One of the structures to downsize the semiconductor device is the structure to flip-chip bond a plurality of semiconductor chips onto one wiring substrate by narrowing a gap therebetween.
An example of a process for manufacturing such a semiconductor device is shown in FIG. 8A to FIG. 8C, which are side views illustrating a conventional process for manufacturing a semiconductor device.
Firstly, as shown in FIG. 8A, solder bumps 103a and 103b are formed in advance on external connection pads (not shown) on the surfaces of semiconductor chips 102a and 102b, and a sealing resin (an underfill resin) 104 before curing is applied to a flip-chip bonding surface on a wiring substrate 101, for example, by a dispenser. Here, a land (not shown) which is an electric conductor for the flip-chip bonding is formed by patterning on the flip-chip bonding surface of the wiring substrate 101.
Then, the semiconductor chips 102a and 102b and the wiring substrate 101 are kept apart from each other in a direction of z, and the semiconductor chips 102a and 102b are aligned (x position, y position and rotational position around a z axis) relative to the wiring substrate 101.
Next, as shown in FIG. 8B, the semiconductor chips 102a and 102b are moved in a direction closer to the wiring substrate 101 (z direction) to be pressed against the wiring substrate 101, for example, by a flip-chip bonder, and are mounted and arranged so as to bring the solder bumps 103a and 103b into contact with the land on the wiring substrate 101. Through these processes, the semiconductor chips 102a and 102b are temporarily fixed on the wiring substrate 101 with an adhesive force of the sealing resin 104.
At this time, the sealing resin 104 before curing is filled into a space between the semiconductor chip 102a and the wiring substrate 101 and a space between the semiconductor 102b and the substrate 101, and is squeezed out from these spaces to spread over the surface of the wiring substrate 101. It is intended that reliable shield from the atmosphere and mechanical structure having a sufficient strength of the flip-chip bonding portions are obtained owing to these filled portions and squeezed out portions (called fillets).
Next, as shown in FIG. 8C, the wiring substrate 101 on which the semiconductor chips 102a and 102b are temporarily fixed is heated to melt the solder bumps 103a and 103b so that mechanical and electrical connection of the semiconductor chips 102a and 102b with the wiring substrate 101 is established, and the sealing resin 104 is cured.
Here, the narrower gap between the semiconductor chip 102a and the semiconductor 102b is more desirable in terms of downsizing of the semiconductor device. However, it has turned out that the design for narrowing the gap therebetween results in decrease in yield as a semiconductor device. According to the analysis of the causes, it has turned out that a major cause results from the fact that in the step shown in FIG. 8B, the sealing resin 104 which is squeezed out from the spaces between the wiring substrate 101 and the semiconductor chips 102a and 102b and is positioned between the semiconductor chip 102a and the semiconductor chip 102b is folded so that a force to widen the gap between the semiconductor chip 102a and the semiconductor chip 102b is generated to cause the displacement of the semiconductor chip 102a and the semiconductor chip 102b from a predetermined position.